Left ventricular deformation and myocardial fibrosis in pediatric patients with Duchenne muscular dystrophy

Background: Left ventricular (LV) strain and rotation are emerging functional markers for early detection of LV dysfunction and have been associated with the burden of myocardial fibrosis in several disease states. This study examined the association between LV deformation (i.e., LV strain and rotation) and extent and location of LV myocardial fibrosis in pediatric patients with Duchenne muscular dystrophy (DMD). Methods and results: 34 pediatric patients with DMD underwent cardiovascular magnetic resonance (CMR) with late gadolinium enhancement (LGE) to assess LV myocardial fibrosis. Offline CMR feature-tracking analysis was used to assess global and segmental longitudinal and circumferential LV strain, and LV rotation. Patients with fibrosis (n = 18, 52.9%) were older than those without fibrosis (14 ± 3 years (yrs) vs 11 ± 2 yrs., p = 0.01). There was no significant difference in LV ejection fraction (LVEF) between subjects with and without fibrosis (54 ± 6% vs 56 ± 4%, p = 0.18). However, lower endocardial global circumferential strain (GCS), but not LV rotation, was associated with presence of fibrosis (adjusted Odds Ratio 1.25 [95% CI 1.01–1.56], p = 0.04). Both GCS and global longitudinal strain correlated with the extent of fibrosis (r =.52, p = 0.03 and r =.75, p &lt; 0.01, respectively). Importantly, segmental strain did not seem to correspond to location of fibrosis. Conclusion: A lower global, but not segmental, strain is associated with presence and extent of LV myocardial fibrosis in pediatric DMD patients. Therefore, strain parameters might detect structural myocardial alterations, however currently more research is needed to evaluate its value (e.g., prognostic) in clinical practice.</p

Chronic ventricular pacing in children: toward prevention of pacing-induced heart disease

In children with congenital or acquired complete atrioventricular (AV) block, ventricular pacing is indicated to increase heart rate. Ventricular pacing is highly beneficial in these patients, but an important side effect is that it induces abnormal electrical activation patterns. Traditionally, ventricular pacemaker leads are positioned at the right ventricle (RV). The dyssynchronous pattern of ventricular activation due to RV pacing is associated with an acute and chronic impairment of left ventricular (LV) function, structural remodeling of the LV, and increased risk of heart failure. Since the degree of pacing-induced dyssynchrony varies between the different pacing sites, ‘optimal-site pacing’ should aim at the prevention of mechanical dyssynchrony. Especially in children, generally paced from a very early age and having a perspective of life-long pacing, the preservation of cardiac function during chronic ventricular pacing should take high priority. In the perspective of the (patho)physiology of ventricular pacing and the importance of the sequence of activation, this paper provides an overview of the current knowledge regarding possible alternative sites for chronic ventricular pacing. Furthermore, clinical implications and practical concerns of the various pacing sites are discussed. The review concludes with recommendations for optimal-site pacing in children

Congenital and childhood atrioventricular blocks: pathophysiology and contemporary management

Atrioventricular block is classified as congeni- tal if diagnosed in utero, at birth, or within the first month of life. The pathophysiological process is believed to be due to immune-mediated injury of the conduction system, which occurs as a result of transplacental pas- sage of maternal anti-SSA/Ro-SSB/La antibodies. Childhood atrioventricular block is therefore diagnosed between the first month and the 18th year of life. Genetic variants in multiple genes have been described to date in the pathogenesis of inherited progressive car- diac conduction disorders. Indications and techniques of cardiac pacing have also evolved to allow safe perma- nent cardiac pacing in almost all patients, including those with structural heart abnormalities

Controversies in arrhythmias and arrhythmic syndromes of active children and young adults

Important advances in the diagnosis and therapy of various arrhythmic disorders have been made in the last two decades. These, in turn, have necessitated a re-examination of current practice guidelines, with a view to deciding on optimal management of young patients with suspected or proven arrhythmia syndromes and in assessing the risk of adverse arrhythmic events during sport participation. There has also been a concomitant emphasis on identifying individuals at risk by nationwide screening programs using the ECG and excluding them from competitive sport. This review identifies some of these issues, looks at the data critically and offers some suggestions for current care and future research

The pathophysiologic aspects and clinical implications of electrocardiographic parameters of ventricular conduction delay in repaired tetralogy of Fallot

The 12-lead surface electrocardiograni is a valuable and feasible clinical tool in the management of patients following tetralogy of Fallot (TOF) repair. The importance of QRS duration in TOF patients has long been acknowledged. A prolonged QRS complex has been associated with increased risk for subsequent life-threatening ventricular arrhythmia and sudden cardiac death. Our current ability to risk-stratify TOF patients for malignant arrhythmogenic events primarily on the basis of QRS duration is rather limited. Nevertheless, increasing evidence suggests that QRS morphology and duration may be useful as surrogate markers of infundibular and regional right ventricular myocardial disease. The aim of this review is to provide a critical appraisal of the clinical implications of established and new electrocardiographic markers of ventricular conduction delay in TOF patients following surgical correction with a particular focus on QRS duration, lengthening, and fragmentation. In addition, the pathophysiological background of these parameters is addressed. (C) 2014 Elsevier Inc. All rights reserved

Use of an active fixation lead and a subpectoral pacemaker pocket may not avoid Twiddler′s syndrome

Manipulation of a pacemaker with consequent malfunction of the device has been called Twiddler′s syndrome. Use of active-fixation leads and subpectoral pacemaker pockets has been considered to help in avoiding this problem. We describe a child in whom twiddling was not prevented despite implantation of a lumenless atrial lead and insertion of the pacemaker generator in a subpectoral pocket

Emerging clinical applications of strain imaging and three-dimensional echocardiography for the assessment of ventricular function in adult congenital heart disease

Management of congenital heart disease (CHD) in adults (ACHD) remains an ongoing challenge due to the presence of residual hemodynamic lesions and development of ventricular dysfunction in a large number of patients. Echocardiographic imaging plays a central role in clinical decision-making and selection of patients who will benefit most from catheter interventions or cardiac surgery.. Recent advances in both strain imaging and three-dimensional (3D)-echocardiography have significantly contributed to a greater understanding of the complex pathophysiological mechanisms involved in CHD. The aim of this paper is to provide an overview of emerging clinical applications of speckle-trading imaging and 3D-echocardiography in ACHD with focus on functional assessment, ventriculo-ventricular interdependency, mechanisms of electromechanical delay, and twist abnormalities in adults with tetralogy of Fallot (TOF), a systemic RV after atrial switch repair or in double discordance ventricles, and in those with a Fontan circulation